By ELEANOR WARNOCK TOKYO—Japan took a step toward revamping its roughly ¥160 trillion ($1.6 trillion) public-pension system, with a government-appointed advisory panel suggesting a shift in some investments from government bonds to higher returning assets like real estate and private-equity funds. If implemented, the steps could signal a sea change in how trillions of yen are invested, unleashing a flood of cash into global markets as well as the Japanese economy. The shift also could affect everything from the government’s fiscal health to the amount of pressure investors put on Japanese companies to perform well. “If you…